Skid-steer loader machines are old and well known to the art. Originally designed to operate with only a loading scoop or a bucket, these machines have, with the provision of specifically designed attachments, evolved into multi-purpose machines capable of many diverse operations. Nowadays, a skid-steer loader machine may be configured to operate as a street sweeper, a posthole digger, a trencher, or a forklift, for example. As the number of applications of skid steer loaders increases, they may be found in use in many different environments. Often, they are used in conditions where the surface upon which they traverse is not capable of supporting the weight of the skid-steer loader and they can become mired and/or lose traction.
These drawbacks can be overcome by using vehicles having permanently installed tracks, or by removing the wheels of a wheeled vehicle and replacing them with a unitary tracked undercarriage. A problem with permanent tracked vehicles is that they are not designed to be converted to wheeled vehicles. A problem with undercarriage systems is that they are also designed with permanence in mind, and they are not easily removed after they have been installed. In addition, they are usually designed for use with a particular vehicle make and model, and are not easily transferable from one vehicle to another vehicle.
Other solutions include providing the skid steer loader with a pair of auxiliary endless tracks that are positioned about the front and rear wheels on either side of the vehicle, or replacement the wheels of a skid steer loader with a sprocket and a system of rollers, about which a rubber track is installed. Each of these solutions also has its own set of drawbacks. With the auxiliary track solution, the pneumatic tires, about which the track is positioned, often do not have the same circumference. This can be due to different wear patterns, unmatched sets of tires, or different inflation pressures, for example. Since the front and rear wheel axles rotate at the same speed and direction (for straight line motion) the front and rear wheels, having different circumferences, will have different ground speeds. This means that friction and abrasion will be generated between the wheels and the track, which can lead to undue tire wear and even premature failure. An additional drawback is that such track add-ons are usually designed to fit a particular skid-steer loader having a predetermined wheelbase length, a predetermined axle length, and a predetermined tire size. With the replacement track solution, extensive modifications are often required. Moreover, the removal of the pneumatic tires often results in a harsher ride.
Another related drawback to existing add-on track attachments is that when the front arms of the vehicle exert a downward pressure on an implement to which they are attached, the front end of the vehicle is lifted up. This reduces the ground contact area of the track and the vehicle looses traction. Moreover, when a vehicle is tipped back on its rear wheels it becomes more difficult to control.
There is a need for track assembly that is able to convert a wheeled vehicle into a tracked vehicle. There is a need for a track assembly that can be attached to existing wheel flanges using lugs and bolts, and which requires no modification or disassembly of the vehicle. There is a need for a track assembly that can be adjusted for use with different wheeled vehicles models and makes. There is also a need for a track assembly that can accommodate a vehicle that has misaligned wheel axles, or wheel flanges, or which can accommodate variations in axle or wheel flange rotation such as runout or wobble, and misalignment. There is yet another need for a track assembly that is able to maintain full ground contact while allowing the front end of the body of the vehicle to be elevated. And, there is a need for a track assembly that is able to attenuate jolts and vibrations from being transmitted directly to the vehicle.